<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>rotate</title>
    <style>
    div {
        position: relative;
        width: 249px;
        height: 35px;
        border: 1px solid #000000;
    }
    div::after{
        content: "";
        position: absolute;
        top: 8px;
        right: 15px;
        width: 10px;
        height: 10px;
        border-right: 1px solid #000000;
        border-bottom: 1px solid #000000;
        transform: rotate(45deg);
        transition: all 0.2s;
    }
    div:hover::after {
        transform: rotate(225deg);
    }
    </style>
  
</head>
<body>
    <div>

    </div>
</body>
</html>